Emergency shutdown system for carbon black plant



R. F. DYE

Jan. 12, 1965 EMERGENCY SHUTDOWN SYSTEM FOR CARBON BLACK PLANT Filed Aug. 11, 1961 2 Sheets-$heet 1 uw Nlzlwolv mm..- mmIPO 20m..-

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A TTORNEYS R. F. DYE

Jan. 12, 1965 EMERGENCY SHUTDOWN SYSTEM FOR CARBON BLACK PLANT Filed Aug. 11, 1961 2 Sheets-Sheet 2 www .VM

A TTORNEYS United States Patent 3,165,522 EMERGENCY SHUTDGWN SYSTEM FR CARBQN BLACK PLANT Robert F. Dye, Bartlesville. Okla., assignor to Phillips Petroleum Company, a corporation of Delaware Filed Aug. 11, 1961, Ser. No. 130,831

3 (Ilaims. (Cl. 2li-259.5)

This invention relates to a safety shutdown systeml for use in processes involving pyrolysis, or cracking of com- 3,165,522 Patented Jan. 12.1965

ice

.charging oil remaining in the tubes. ln many Vcases the Acoils or tubesin which the charge stock is being preheated bustible hydrocarbon mixtures. In one aspect it relates to automatic safety shutdown systems for use in carbon have been actually ruined andhave required replacement with a consequent measurable increase inmaintenance and replacement costs.

' In carbon black production `reactors employing only air tangentially, charge oil `failure with continued air ow results in production of a highly explosive atmosphere in the reactor and in downstreamy equipment at least for a short period of time. l

Manual shutdown of the various supply sources to prevent hazardous conditions fromarising has often been unsatisfactory because of the ineiiiciencies and uncertaincontains carbon black in suspension and is conducted l. through a suitable header to a quench unit and subsequently to agglomerators and bag lter units for Vrecovery of the carbon black from the vsuspending gas. In a lconventional carbon black production process such as that disclosed in AUS. Patent 2,641,534, or Patent12,564g,700, a heavy gas oil or natural gas is preheated in a vlir eetiired preheater or in an indirect heat exchanger installed in the eluent or smoke pipefdownstreamA of lthe carbon black, reactor. The hydrocarbon charging stock*I is thus preheated to a predetermined temperature and it isjthen fed axially into the reactor along with a small stream of `process A fuel mixture such as a mixture oflrratural` gas, or oil and air, or air alone, `is fed tangentially/into v the reactor so as to heat the hydrocarbon charging stock to pyrolytic or cracking temperatures. p

` -a part of thisspecification. Y Y

l In Ythe drawing, FIGURE` l' illustrates, in diagrammatic form, an arrangement kof apparatus parts suitablefor'fus'e fin safely shutting down ancarbon black production system The eluent Yfrom the carbon black reactor contains l e carbon black Vsuspended in a stream of flue gases. These gases contain.' a substantial -quantity of, hydrogen, for example, about l2 volume percentorv more,A and `carbon monoxide, also in about l2 volume percent o rY more, on a dry basis, as Well as traces of hydrocarbons. Y Carbon dioxide gas is also present. Since a deficiency of air is employed as regards the feed oil and tangential fuel, all or substantially all of the oxygen is consumed in the partial combustion. However, in the event of a pressure-failure within the plant productionfsystem due :toaxial oilor tangential fuel failure without failure oi process air, vthis process air can enter through the smoke headers d oWnstream of the reactors, quench unit, etc., whichfcontain k ties of manualshutdown systems.

Furthermore, employment of manual shutdown systems has .attendant diiiculties in insuring proper sequence of shutdown operations, as Well as proper sequence of starting up operations.V f

Y Accordingly, 'an object of this invention is to provide an improved automatic safety shutdown system for use in furnace carbon black processes. Another objectof this invention is to provide an automatic safety shutdown Vsystem for usel in carbon black processes'sothat failures Y of electric power, Yprocessvain or the like, will not give rise to explosive hazards kor other undesirable conditions. Still another objectofthis inventionv isto provide an improved safety shutdown system for carbon black .pro--4 cesses wherein coking ofthe hydrocarbonA charging stock in the preheater tubes is `prevented if a charge stock supply failure occurs. Further objects, and advantages of `this invention. will be realized vupon reading the followingy description which, taken with theattached drawing, formsV whencertainlprocess'failures occur. FIGURBZ illusf Y trates, in'fdiagramma'ticform, another arrangementv of apparatus parts suitable forcarrying outl the-shutdown operations of afcarbon black production ofcertan process failures. Y i The apparatus illustrated fn FIGURE 1 is directedl-to use in afl-line. system. VBy the term l-line is meantY the employment of asingle carbon Vblack collectionsystem lfor the collection of carbon black fromsimilar orfrom different types of carbon black reactors producing 'different' combustible gases.4 This air gives rise tohhazardous conf,

ditions which can result in anexplosion due to the presence of the hydrogen.V and carbon monoxide. Such ya mixture can be ignited on contact with the heated :surfaces of equipment. 'Reduced pressure in-thesystem .can develop from failure of process air, tangential fuel, axial oil, purge steam and system cooling.

l Under. these conditions air is drawn into the system. 1

Furthermore, av failure in the I'process air 4supply cause combustion gases from the reactorto hack up into also result in severe coking inthe reactor.

Also, interruption or failure onf-, the Y tangential" fuell sir'ahle operating conditions, Yespefiilally;where supply of process air is continued.v

Failure in the supply of hydrocarbon char-ige, stock result inundesirable cokirigin the: preheater tubessince' the residual heat inv the hot {refractorfies of thenpreheater is Vusually'suliicient to cokea substantial portion of the f types of carbon black. Such a l-,line system is so arranged that only one type of reactor producing .one kind f. carbon l u black canbe operated at a timebecause of the single A collection system. At any subsequent time when another type of carbon black is desired,either the original reactor is operated ,under different operating conditions or another v reactor isA used.V In other words, onlyfasingletypeofl carbon black can bel-produced and ,collected atoneV time in the` 1,-line systernf` Y v In the 2`line system,

i rate carbon black collection systems are provided. In this the air supply header. with the ,result that a further explo- Y 'Y sive hazardmay exist. `Failure of;process air supply :auction of the casethe two different typeaof carbon black reactorscan bepperatedat rthe same timel'with each reactor passing its efuent gases containing carbon'black in suspensionfto the respective carbonbIack collectionsystems..

` Inteitherof the lfline or-,2-line'carbon2black production j `systems more than one reactor can ibe used in place of the singlereactor illustrated'in theadrawing.- l f y v n AIn thed-rawing, audinrefere'ncetog-EIGURE 11; .refer ence 11 identities aV carbonbla'ck producing ,reactor herein", termedanHAEfISAF reactonr TheHAF'refersfto proi n i gh abrasion, t'urnacefc'arbtm black 'and' I the refersfto Van `intermediate super-abrasion fur- `i nace carbon black.; l YA conduit,12 4leads the carbon black` producing charge' o il from asource, n ot shown, to'the* carbon black production system. -A normally 'open valvelV system in case#- illustrated lin FIGUR 2, two sepa- 24 is provided and is maintained in a closed position so that charge oil will be forced from conduit 12 to the several reactors in this figure. A conduit 13 is provided as a return conduit for the charge oil under certain abnormal or emergency conditions. actor ll'charge oil from conduit 12 is passed through a conduit 18 and through aheat exchange coil in aheat exchanger or-preheater 21 and through conduits 20 and 14 and charged to the reactor. A diaphragm valve 16 is a normally closed valve maintained in-an open position during normal plant operations. A conduit 15 is provided at the end of conduit'20 for return of the carbon black charge oil to return conduit 13 under abnormal or emergency plant conditions. A valve 17 is a normally open valve but is maintained in a closed condition during normal plant operations. Pressure switch 22 is a high pressure switch and is adapted to sound an alarm 23 in case the charge oil pressure exceeds the predetermined pressure such as 125 pounds per square inch gage. Another pressure `switch 22a is provided, as illustrated, for sounding an alarm 23a' in case the pressure of the charge oil drops to a pressure below a predetermined pressure, such as 75 pounds persquare'inch gage.

A conduit 25 is providedffor passage of tangential fuel, 'that is oil or gas "as the case may be, from a source, not shown, to the system illustrated-in FIGURE l.r From conduit 25 oil is passed through a conduit -28 with a portion passing through a conduit 31 to separate heat exchange coils'i'n the heat exchanger 21.- From these separate coils the two portions of tangential oil pass by way of `conduits `and 33 to separate tangential inlets or burners in the reactor;y Y y l A valve 19 is providedbetween the charge oil line A18 and the charge oil line 2t) in case all or a portion of the charge oil to be introduced into the furnace can by-pass the heat exchangerz'fSimilarly, valves 29 and 32y are provided in by-pass 'fuel conduits-.betweenconduits v2hV and 30, and 31 and 33,'respectively,incase all or a portion of the separate streams of tangential fuel are desired to be by-passed from the heat exchanger. Y Y I Process air .isprovided for supporting combustio'nof thetangentially added fuel; Such process airiis provided under pressure by a processair blowerY 46 which, in the In the operation of re.

oil the valve 74a is closed and a normally open valve 75a, which is maintained closed in normal operating conditions, is opened for the by-passing operation.

A 10W pressure, pressure switch 76 is provided for Sounding an alarm 77 incase the pressure of the charge oil in conduit 73 is reduced to a pressure below a predetermined pressure such as 75 pounds per square inch gage. A high pressure, pressure switch 76a is provided for sounding an alarm 77a in case the pressure of the charge oil in conduit 73 exceeds Va predetermined pressure, such as 125 pounds per square inch gage. A source of electrical current 94e is provided for operation of electrical alarms 77 and 77a by way of the pressure switches 76 and 76a, respectively.

Oil for use in heating up reactor 78, when` it is desired to place the cold reactor in operation, is passed from the tangential oil fuel line 25 through a conduit 80, through a manually operable valve 82 and through a pneumatically operablevalve 83 into the oil charge line 74. In this reactor heating operation a paraiinic oil is used because it can be burned completely without any carbon laydown. This tangential fuel oil is added through conduits 80 and 74Y during the warming up operation. A ow recorder 81 is employed in order to record, for permanent record purposes, the rate of flow of oil used during the Warm-up. The manually operable valve 82 is provided in conduit 80 for permanently closing olf the ow of the warm-up oil after the warm-up operations. A conduit 84 provides a supply of atomizing air for atomizing the carbon black Vfeed oil. v

Process air for the `normal operation of reactor v78 is taken' from conduit 47 through a branch conduit 86, with portions passingthrough conduits 87 and 88. A rate of ow controller 91- regulates the rate of ow through a diaphragm 'valve 89 for passage of a predetermined flow of air through'conduit87, a portion of which isintroduced tangentially into the reactor and `a portion being introduced'parallel with the charge oil for cooling the charge case illustrated in` FIGU-RE'II, is an'electric motor driven air blower. The etliuent airfrom blower 46 passes through a conduit 47 with 1.a.- portion of the air` passing through a conduit 48 with portionsY thereof passing through conduits 49 and =57. The Y portion Vpassing through Yconduit 49 is passed through .conduit 51 only (a small volume) for warm up of the reactor. When this equipment is sutliciently heated for operationfconduit 51 is closed and conduit 49a opened for large volume airflow in normal plant operation. Likewise, conlduit 59 is used for small volume air ow during warm up only and conduit 5S is used for large volume air ow for normal plantoperation. Air passes Vthrough conduit 55, .as axial air; onlylduring production of carbon black.

Reference. numeral 78 identities an FEF-GPP carbon black reactor. The term FEF refers tofast extrusion furnace type carbon'black while the term GPF refersV to a furnace for production of a general purpose type carbon black. A conduit/71 is. connected with the charge oil conduit. 12 and leadsV the charge oil `for use in reactor .78*to a coil in heat exchanger 79.Y The outlet of the coil in the exchanger` is connected with a' conduit 73 through which the heated oil flows forcharging through a charge Aconduitg74 ori-for by-passin'g the reactorv by owing Vthrough a return conduit 75. l VUnderthis latter condition thelreturn or recycled oil entersl the conversion, oil' return yconduit 13. f A valve 72 isprovicled for bypassing all or a portion;l or Anone ofthe charge oilfaround'the preheaten .For passing the charge ciilY lthrough -conduit"74" ihto'the oil injection nozzle. The portion of the process air passing through conduit 88 is regulated byfoperation ofdiaphragm valvev- 90 in response to the setting of the ow f rate controller apparatus 92. L Air passing through conduit 88 .is also introduced tangentially into reactor 78. Inthis type of reactor, that is, the FEF and GPP, fuel is'not introduced tangentially into the reactor lforlburning with the -tangentially added air. In this case a portion of therconversion oil charge stock is burned by the tangentiallyadded air for providing heat for carrying out the carbon forming reactions. i

In this 1-line system the carbon containing gaseous etu'ent from reactor 11 passes through heat exchanger 21 and thence to a smoke header 121 while reactor 78 is Y not in operation. When reactor 78 is in operation, furnace euent containing carbon black therefrom is passed through the heat exchanger 79 and into the smoke header 121. In this manner only a single'type of carbon black is introduced into` header 121V at a time and such furnace etllue'nt containing carbon black is passed on through a conduit to the collection system which, in many cases, includes fcycloneseparators, bag filters and the like.

'i' The safety emergency shutdown system of this invention includes.A a `conduit 128 leadingfrom the source of constantV pressure compressed air.4 ThisV air, sometimes called instrument air or shutdown air, passes through a three-way solenoid valve 129. The following conditions close this solenoid valve from the source of air and open ,a bleed, to reduce the; pressure in conduit 128 downstream of the solenoid valve; An electrical circuit 94h supplies electrical power from a source; not shown, through seve'ral switches and relays and thence to the solenoidvalve 129. "Beginning at the end of circuit 94'b remote kfrom the solenoid valve 129 the circuit passes through a pressine-switch'106'. Carbon black containing gases pass to a bag lter unit during normal operations. Pressure-switch 106 is set to break the circuit 9411 when gas pressure in conduit 135 exceeds a predetermined pressure. Thispressure is communicated to a transducer 67a which regulates instrument air pressure in a conduit 67 which, in turn, transmits the pressure signal to the pressure-switch 106. Thus, when the pressure inconduit 135 exceeds a value of, for example, 12 inches of Water, pressure-switch 106 breaks the circuit 94b. A pressure recorder 108 records .pressure in conduit 67 while an alarm 107 rings a bell or lights a light tor attract the attention of an operation when the pressure-switchopens the circuit 94b.

As mentioned hereinbefore, tangential fuel oil is transmitted to system through conduit 25 and is thus passed through branch conduit 2S for normal operation of reactor 11 and through branch conduit 80 to the FEF reactor for warm-up purposes only. A normally closed, pneumatically operable valve 27 is a throttle valve and is operated as aback pressure valve for maintaining a predetermined back pressure in conduit 25. In case of `a marked drop in fuel oil pressure as occasioned by such 'conditions as breakage of pipe, failure of the tangential Vfuel oil pump, or other reasons, pressure in conduit 25 decreasesbelow a normal operating pressure. A pressurefswitch 103 senses the pressure in fuel oil conduit 25 by way oi-r an instrument air conduit 56' and as longjas the pressure is maintained at a normal operating'pressure in conduit 25, suchy as-100pounds per square inch gage,the switch of the.pressureswitch is maintained closed, completing the circuit .94b. However, uponl a decrease in the fuel oil pressure below a predetermined pressure, pressure-switch 103 breaks the circuit 94b'thereby closing solenoid valve 129 to the source of instrument air'. A hand-switch 99 in a by-pass circuit 98 around the pressure-switch 103is normally maintained open and thishand-switch is closed,

if desired, to permit operation of the FEF or GPR system (excepting FEF or GPF reactor warm-up and holding) while the difficulty `causing the drop in the fuel oil pressure is'being corrected. After the diiculty is corrected and oil pressurefin conduit25 reaches its normal operating pressure, theV pressure-switch. 103 closes and handfswitch 99 is opened. A pressure indicating controller 105 is provided, as illustrated, to operate a motor valve 27 for pressure maintenance in conduit 25. When valve 27 is open, tangential oily iiows through conduit 25, valve 27 andthe portion not used by the reactors returns to its storage through a conduit26`. alarm 104 can be a bell or an electric light to warn an-operator when pressure. switch 103 opens circuit 94h. Y

Y 'Conversion oil for the production of carbon black in either vof the reactors originates from a source, not shown, and is passed ,through conduit 12, a normally closed back pressure pneumatic valve 24 and is returned toits Vsource throughconduit 13. During normal Voperations .vali/e224 is maintained open for pressure` maintenance in conduit 12 by a pressure indicating controller 102. This con. troller is actuated by instrument air from a conduit 68, the pressure inr which is regulated by orf-is'proportionalV tothev conversion'oil pressure in-conduit 12.'

It, for some reason, conversion' oil pressure in vconduit A hand-switch 97 `is provided in a by-'pass circuit around pressure-switch 109.` -'During normal reactor operation pneumatic valve 24 is maintained closed by `the pressure which can be one or more blowers, pump process air through conduit 47 and thence to various process points of the apparatus in FIGURE 1. Upon a drop in shutdown air pressure in conduit 128 downstream from the three-way valve 129, this pressure drop is sensed in conduit 130 and in conduit 163. The pressure drop in conduit 130 actuates a pressure switch 131 in circuit 94a thereby opening power switch 132 in power circuit 94-96. Blower 46 is thus closed down. With the pressure drop in conduit 163, valve 164 opens to bleed pressure from conduit 70 thereby allowing valve 165 to close. Also, three-Way valve 168 opens to bleed and normally open valve 93a opens to vent process air from conduit 47 through vent conduit 93. When process air pressure in conduit 47 drops to below 2 pounds per square inch gage, pressure switch 116 opens while it remains closed above this pressure.v At pressure below 3 pounds in conduit 47, pressure switch 116 is closed' while it opens at a pressure greater than 3 pounds. The pressure switch 118 is ina by-pass circuit 115 around pressure switch y116 and a hand-,switch 117. This by-pass circuit also contains a hand-switch 119. Thehand-switch 119 is a push button switch for .starting up the operation. The pressureswitch 118 is closed when process air in conduit'47 is at a pressure from O toY 3 p.s.i.g; and opens when the process air pressure exceeds 3 p.s.i.g. and thus de-energizes the hand-switch holding coil.

As mentioned hereinbefore, pressure-switch 106 opens the circuit 94h when the pressure of the carbon black containing gas passing through conduit 135 to the'bag filters exceeds 12 inches'of water. rPressure switch 103 opens the circuit. when the ltangentialpoil pressure decreases to a value below normal; pressure-switch 100 opensthe circuit whenV the conversion oily pressure decreases'to a value below a predetermined value and the pressureT switch 116 .remains normally closed but opens when the process air pressure decreasesto a ypressure of about 2 p.s .i.g. whilevpressure-switchll is closed when process Y air pressure is from 0 to 3 p.s.i.g. and opens when the process `air.pressureexceeds 3 p.s.i.g. Hand-switch 117,

Aupon being opened, shuts down the system and when pres l sure switch 116. senses 2v poundsV or fless pressure in con-- duit 47, it Aopens and remains open and shuts down the i system. AHand-switch 119 Vis a push button switch for starting upA the operation.Y When starting up the operation, pressure switch '113 isV closed untilthe process air pressure reaches 3 pounds and at pressure,lpres'sure switch 118 opens but pressure switch 116 had closed at 2 pounds process air pressure. Thus, switch 116 the circuit 94h for normal operation.'l n

When any of `these aforementioned conditions occurs .to open the `electrical circuit94b, the following operation` Y `alor shutdowrrstepsoccur. .The Vsolenoid of valve 129 becomes d'e-energized and thisfvalve closes oit the source `of shutdown air andjallows the bleed to reduce the pres- .l

surez in conduit 1`23l`downstream of valve 129 and the branchconduits therefrom. Upon the reduction of pres- Y, sure Vinconduit 128 downstream of valve 129,V pressure in indicating controller 102for pressure maintenance in con-v Y. i n -duit12but-during anabnormal drop. in conversion oil f pressurefvalve 24 is openediby `bleeding o tf'of instrument lair pressure by controller. 102'." An.Qalalrrn. 101,V canbeacaused by `opening a pressure-switchlt);

The emergency shutdown three-way valve1-129falso controls the process air blowers.46 .y These blowers,

conduit -137 decreases' thereby actuatingthreeway'valve 161 to bleedfin'strurnent air pressu'reffrom conduit 150` thus closingnormally Vclosed valve 162. At the same time vreduced air pressure; in-vconduit-148'actuates three-way p valve -158 vtorbleedairpr'essure from instrument air'con-A duit 149 thus opening normally open valve 159 and allow-i .ing the ogasl normallyipassing -throu'ghfcondui't `156 vto 7 vente-through'vent conduit 157. YThis vent conduit. 15'lfisV usually connectedV with the boiler stack, not ,showin-` j f At the same time, a reduction ofair pressure inb'ra'nch conduit 148 actuates three-way valve 155 tobleedin- .,strurnentar pressure from. conduit 143 therebyallowing inghnormally closed valve 152 to close. ,Atthelj sametime'. threewayvvalve 151. is actuated; tri-bleedr AairI pressure.

from` conduit -142 thereby allowing.;normally open *valve A. `V1 53ftoopen.therebyjventing off-'gas normallyy passing through conduit 147,V through conduit f1'5,42'to the-pellet* closes'.

dryer stack, not shown. An extension of branch conduit 148 is identified in the drawing by reference numeral 138 and this extension leads to other operating equipment. Thus, Vas the instrument air pressure in branch conduit `137 decreases, pressure in branch conduit 138 also decreases, thereby opening normally open valves 145 and 146 to allow steam from conduit 144 to pass to boiler pumps, not'shown.` Also, a reduction of pressure in eX- tension conduit 138 actuates the three-way valve 140 thereby bleeding instrument air from conduit 14th: which, in turn, allows normally open valve 141 to open, thereby venting the olf-gas passing through bag filter repressuring blower 134 through conduit 136. When this vent valve in by-pass vent conduit 136 is closed, the ofi-gas from conduit 135:1 passes on through the blower 134 to the bag lter repress'uring operation.

Element 133 is an electrical interlock and this interlock prevents operation of the bag lilter repressuring fan, or blower, 134 when the process air blower or blowers 46 are shutdown. In other Words, when pressure-switch 131, which is responsive to pressure in branch conduit 130, operates to break circuit 94a, switch 132 opens the power circuit source 94 thereby opening circuit 96 to the process air blower 46. Thus, with this 'latter circuit open, the process air blower is closed down and the abovementioned interlock by way of circuit 95 opens switch 133 thereby opening the power circuit to the bag filter repressuring fan V134.

When instrument air pressure in conduit 128 decreases, pressure in branch conduit 163 also decreases thereby actuating three-way valve 164 to bleed air pressure from conduit 70 thereby closing the normally closed valve165.

Also, this decreased air pressure in conduit 163 actuates the three-Way valve 168 to bleed air .pressure from the normally openl pneumatic valve 93a and thereby opening conduit 47 to vent. i

A drop ofpressure in conduit 128 also drops pressure in branch shutdown conduit'177 thereby reducing pressure in branch conduit 178 and actuating three-way valve A44 tovent pressure from the diaphragm of Vnormally closed valve 16 allowing this valve to close and from the normal- Vly open rValve 17 thereby allowing this latter valve `to open. In this manner conversion charge oil ilowing through con- Yduit 20 is by-passed from reactor 11 and returned to recycle line or conduit 13. Three-way Valve 44a is providedfor operating pneumatic valves 16 and 17. Thus,'in strument air passing through conduit 42 and through three-way valve 44, in its normal operating position maintains valve 17 closedfand valve .16 open. If at any time it is desired to close off conversion oil from reactor 11, hand-switch 45a is opened thereby opening circuit 45 and de-energizing the solenoid of'valve 44a-thereby venting instrument air pressure fromfthe diaphragmslG` and 17 which venting in turn closes valvev 16 and opens `valve 17.

The aforementioned reduction ofk pressure in vbranch conduit 177 actuates the Vthree-way valve'179 to bleed pressure from the normally closed valves 61 and 62 thereby permitting these'valves to close therebyV closing ol flow of process air through conduits 58 and 59. Valving, ynot shown, is provided in the instrumentv air conduitsleading from valves 61 and 62 and inthe `diliferential pressure..

conduits leading from conduits'58 and S9 for communication with flow controller. so that branchvconduitV 59k passes process airrtowreactor` 11 during the warm-up Vperiod of the'reactor prior to normal operation and branch conduit 58 passes air to the reactor 11 during normalV` operation.'r A' Pressurereduction in conduit 128 also causesV pressure being warmed up prior to operation'or if the reactor is being operated for the production of carbon black.

The pressure reduction in conduit 128 also reduces pressure in branch conduit 41 and branch conduit 40 thereby actuating three-Way valves 38 and 39 to regulate or close ot the flow of tangential fuel to valves 35 and 34. FloW'recorder-controllers 36 and 37 regulate the rates of llowof the tangential oil through the respective heating coils in exchanger 21, one ow being added to one side of the reactor 11 and the otherstream ofV oil being added to the other side of the reactor.

Pressure reduction in conduit 12S reduces pressure in pneumatic normally open valve 127 thereby opening this valve to allow steam from conduit 122 to pass through either conduit 123er conduit `124 depending upon whether..reactor 11 or 78 is in operation. If reactor 11 is in operation, a manually operable valve 188 is maintained open while a manually operable valve 189 is maintained closed. With valve 188 maintained open then upon opening of valve 127 steam passes from conduit 122 through` conduit 123 and valve 188 to purge the Vportion ofthe smoke header 121 which is passingV the furnace efuent from reactor or reactors 11. In likemanner, in case reacf tor or reactors 78 are in operation with reactor or reactors 11 being closed down, valve 188 is closedand valve 189 is opened. Then, iupon passage of steam from conduit 122 through conduit 124 the reactor 78 portion of the smoke header is purged.V A hand-switch 125 in electrical circuit 94d is provided for actuation, of solenoid valve 126 injcase' it'is ever desired .to purge they smoke header-while pressure in conduit 128 is at its normal'operating value. In this case upon de-energizing the solenoid valve 126 air pressure is bled through the three-Way valve from pneumatic valve 127 thereby opening this valve for the passage of steam.

A reduction of shutdown air pressure ,in conduit 128 reduces-air pressure in branch conduit 182 thereby yactuating three-way pneumatic valves 184 and 185 to bleed pressures from conduits 186 and 187 lthereby closing valves 90 and 89l respectively. A hand-'switch 110 in electrical circuit 109 is provided Vfor manually de-energzing or energizing the solenoid of the solenoid valve '183.`

ing air ow is closed olf; Instrument air from a source,l

not shown, reaches valves 83 and 85 by way rof a` conduit 176. v Y

Abranchcircuit 112 is provided with za hand-switch 114 for opening and closing electrical circuit to the solcnoid of a three-way solenoid valve 174. This solenoid v valve 174 allows instrument air pressure to be maintained in a conduit 172 which branches andleadsfto .diaphragm valvesV 74a and 75a. Valve y74a is a normally closed valve andy valve'75afris a normally open valvefand upon actuation of three-way valve 174 to bleed, air

reduction inbranch conduit 180.1 Pressure reduction in A conduit189-'actjuates athree-way valve181 toclose nor-V `mally `closed valves 5,3Y and 54. Allow recorder-controller 52 is set tocontrol either the iiow of air through 53V or throughvalvef-S dependingV upon whether the reactor-is pressure from conduit 172' causes valve 74a to close 'and valve 75a to open thereby permittingrecycle and return of conversion oil byl way of conduit `75 tothe recycle v conduit 13.V 1 A A reductionA in the shutdownjair pressure in conduit 128. furthermorev reduces the air pressure in-co'nduit 170 thereby actuatingfa three-way pneumatic 'Valve 171` to vent instrument air pressure from conduit 1,72L and closing f valve 74a and` .openin`g,valve 75a to the above-mentioned recycle. VA yreduction off-pressure lin conduit 170 also reduc'es; pressure inv branch conduit 173 which reduction `actuates, a three-way pneumatic valve to bleed instruv 9. ment air pressure from thepneurnatic valves 83-fand85 thereby closing these valves.

v Also pressure is reduced in branchv conduit 163 for actuating a three-way pneumatic valve 164 which bleeds pressure from instrument air conduit V'70 thereby closing thenormally closed valve 165.

In summary for the shutdown operation illustratedin FIGURE 1, upon failure yof the electrical supply, upon increase in the off-gas pressure. to the bag filter above closes oft the rlow of tangential oil -and also closes ott the process air. In case reactor or lreactors 7S-are in operation the reduction of air pressure in conduit1 12S closes oft conversion oil to these reactors and opens same to recycle While closingof process air tothe reactors. Also purge stream is admitted to whichever section `of the smoke header is in use.

On reference to FIGURE 2 of the numerals 201 and 202 identify the conversion oil feed line and the return line respectively. This feed oil'passes" from conduit 201 through Vbranch conduit203 to a heat exchanger 211 and thence through a conduit 204 to conduit 205 to an HAF-'ISAF reactor 200 when a pneumatic Pressure-switches 207 and 208 along with alarms 209 and 210l operate in the same manner asexplained'hereinabove drawing, reference n Y v in'fthis downstream section of the conduit. This pressure .l `reduction `reduces pressure` in the branch `conduit V.247*v thereby causing pressure switch -353 to 'open electrical vcircuit 217:1 which, in turn,'opens a switch 354 in power Ycircuit 217 thereby closing4 down a process air. blower 216.r With circuit 217 open and process air blower 216 shut down, an' electricalinterlock operates Vby way of circuit 327 l'and closes hand-switch 330to closedown a baglterrepressuring fan 360'andV also to close down by way of hand-switch 331 a'bag iilter Vre'pressuring fan 361. Bag filter` repressuring fan 360 normallyV operates Y to repressurethe vbag lters separating carbon black from normally closed valve 277 is open, or through conduit 206 lwhen a pneumatic normally open valve 276 is open. l

in reference to FIGURE l( A conduit 212' is provided forv collecting eluent gases containin'g'carbon black lin reactor 200 while fan 361 operates for repressuring theV bag filters separating carbon Vblack from reactor 363.` yThis interlock circuit also opens the switch in circuit 307 for opening a circuit 32S to bag filter cycle-timers operating'in conjunction withvth'e baglter separating carbon black `fromreactor 200. Also this interlock operates to open a :circuit 308forclosing down bag filter cycle-timers operating in conjunction with bag filters separating car--` l eiuentfrom reactors `363" by waybf bon blackffrom the circuit329. With the process airblower' 216 closed down, pressure kinprocess air conduit219 drops and this drop inpressure Y switches 355, 356, alarm 359; and hand-switches `357 and 358 in the same manner as explainedrelative to the correoperates by way of conduit V240 :tooperate pressureL spending parts ofiFIGURE 1. V v

TheV drop in shutdown instrument air pressure 'in conduit l227 downstream of valve V2727dec`rease`s pressure in a branch conduit 248 which opens'a three-wayvalve259 .to bleed therebyclosinganormally closeddiaphragm` --valve 2182 in conduit 219.` Afpre'ssure recordericontroller z 352 records pressure in conduit'. `219,` controls lpressure in conduit 219by way of a three-way Vvalve253, conduit 241 and normally open pneumatic valve 283. Forplant shutdown purposes a drop in shutdownairpressure, inV

Y conduit 248 Yopens valve 258 to` bleed pressure from consuspension from one'or more reactors 200 Vand for deliveringthe production effluent to af'conduit 2131er passage to the HAF-ISAF carbonblack collection system. f

A conduit 214 conducts ,tangential gas from a source,

not shown, with branch conduit 215 leading to reactorv 200 and branch conduit 296 leading toone v'or more FEF- GEF reactors 363. A process air blower 216, which is electric motor driven, passesrair through a conduitr219 with branches 220 and 302leading to the respective re` duit 241,thereby opening valve 283 to'yent conduit12'19. A-dropA m the shutdownA air pressure reduces air pressure` in fcondutV 228 ltherebyreducing pressure'in con? duit 229 and by way of'a `pressure-switch 332 landhand 4 switch 330 closingdown the"HAF.-`ISAF 'bag filter-repressuring fanand cycle-timerathat is baglter-cycle-timers, to which circuit 328;1eads.- vThereduced-pressure in conduit 229 also opens a three-way valve 256tofbleed pres sure fromV a diaphragm `valve 273' Vtherebyallowing noractors. Branch line 220-is provided' with a by-passfof Y branchiin'e 221; Conduit 302 conducts process air tol a heat exchanger 301 and thence through a conduit 3056- to vone Vset of Vair inlets. A branch 303 conducts air yfor laxial introduction into thereactor 363l while'fa branch line V304 therefrompasses another portion of -the process air to heat exchanger 301 and thence through aconduitf 305 to Vanother set of air inlets. Reactor. 363 (FEE-GPP) vis not provided with tangentialV burners sincebnly air is injected tangentially into .this reactor.

The Vcarbon black producing apparatus of IGUREZ is a 2-line` system, that is the: reactor orfreacto'rs 200 and the reactor or'.l reactors 363 can be operated to produce their'respective typesv of carbon black at the "same time. As illustrated. in this ligure,1asm'okel headerv212A and a smoke header 301:1 are separated bya blind' a'nge 364 or, if desired, these separate headers can be^completely separated conduits. 4While header 212y passes its product by way of1conduit`213` to itsfcarbonfblack collection system, header 301a passes its content by .way

oftthe conduit 3011) to its particular ,carbon black` Vcol-` lection system. f l

Upon electric powerI failure, as, for example,r byvfrailure of the source of electric power towhich-circuit 309'is connected the solenoidof thethr'ee-way solenoid valve 272is de-energized andclosesroi lthe source of shutdown l 4air, from conduit 227 and opening conduit '227' downstream ofthe valvei 272 to bleed,therebyj,reducingthefpressure 'mally open valve 273 to open and vent any gas passing .through the blower 360 to the atmosphere byway-of con.- duit 3,20. Air pressure isalso reduced inaV branch con` duit V23,0thereby'actuating valve 252 to bleed pressure from the diaphragmsof valves 276 and 277 thereby allowing normally 'closed valve 277 toclose andV norn'iallyl .open

Vvalve 276 to open thereby recycling conversionoil.

i fShu'tdown air pressure lalso jdecreases in' branchconduit 231-.which pressure decrease iactuatesra, thjreefway avalve' 253to bleed instrumentair from'tiie diaphragmof valve 272iV in conduitV 23d to fallow `the normallyjlclo'sed fvalve` 278.10 close thereby closing 'off' tangential gas?V tol lc'tor g 'i A20,0. n In normal loperation,l a iiowY rate recorder-con.,` j I troller 342 .regulateszthe rate-.Coffow andfrecords same in conduit-215 by manipulation of valve 2.78

Shutdown air pressure also decreasesin valve v280 regulates als all ,flo'Wof airand'when norfrnal Voperation-valve r2ttl'is'lzlosel,andy valve y2791 .regulates f a larger rate ofowfof fair. A'fow lret:orderv-,controllerl -343 vrecordsthe'ratcfzs'ofliiow of processlairthrough branch conduit 221 kor throughl5220a,whichevergis being,` used. f`. This reduction in the'ljshutdownarffpressure isfalso corni` y Y' municated to the diaphragm of a valve' 325=in steam con?- branchement' 232 thereby actuatingthreegway pneumatic valves 254 and 255 to lbleed `ai'rpres'sure from the diaphragrns `'offdii aphagr'n valves"279` and 280 by' way of-fconduits 235a'nd' 236 respectively,y thereby allowing the normally 'closed'k valves 279 and 280 tojclosef In starting up reactor 2.00',

1 1 duit 226 thereby allowing .ow`of purge streamrorn conduit 22S to flow through conduit .226 for purging out combustible gases from header 212.Y V

With respect to the operation of the FEF-GPFreactor 363, the decrease in shutdown air pressure is communicated from conduit 227 to conduit 250 and thencethrough a conduit .249 to actuate a three-way valve 257 to bleed air pressure from the diaphragm of valve 274 therebyallowing the normallyopen valve 274 to open thereby allowing gases from the blower 361 to pass through a conduit 322 'to vent. Conduits 238 and 239 conduct instrument air from sources, not shown, to the respective diaphragm valves 273`and 274. Y

The drop in shutdown air pressure in conduit 249 actuates a .pressure-switch, 333 which opens a circuit through hand-switch 331 thereby opening power circuit 308 to shut down the blower 361 and to shut down the bag lter cycle-tmers'actuated through circuit 329 which .operate the bag filters separating carbon `black produced in reactors363.

The reductionin shutdown air pressure in conduit 250 also actuates a three-way valve 260-thereby .shutting off instrument air pressure fromconduit 244 and opening the diaphragms of Valves 287`and 288 to bleed.` This operation allows normally closed valve 288 to close and.

normally open valve 287 to openV thereby by-passing the .conversion oilk to. recycle.

The drop in air pressure in branchconduit 250 is also communicated with the diaphragm of the three-way valve 261 under which ,condition valve 261 is actuated thereby closing off instrument air pressure from conduit 243 and bleeding pressure from the t diaphragms .of diaphragm valves 285. and ,286.' Since valves 285 and 286 are nor-V mally closed valves, this voperation closes these valves.

thereby closing or closed.

However, in normal operation a manuallyoperable valve 284 is closed to` close off flow of warm-up gas through conduit'296 since the atomizing air; in yconduit -362 is intended-for use only with the charge oil-introduced maintaining the valves 285 and 286 into reactor 363 by way of a conduit 299. j Y

'Ihe reduction of shutdown'air-pre'ssure in-iconduitk251 actuates `three-u /ay valves 2,62 and 263. thereby bleeding instrument air pressure from'the diaphragms of valves t 289 and-290 by way of conduits 246 and `245, respectively,

ythereby allowing these normallyy vclosed .valves to close".V

Flow recordercontrollers 346 and 347 in normal operation of the system record thel Hows of process -airthrough conduits 302 and 303 respectively -by control or regulation of the ow control valves 289 and 290. i' i The .drop in shutdown 'air pressure also actuates dia- V phragmivalve 326 therebyopening conduit 324 to admit steam from conduit 225fto the header 301:1. If pressure of the conversion oil drops below a'predetermined value,Y prg-:ssure-switch 337 opens circuit 311, and if thetangential fuel pressure in conduit;Jr 214 drops below predetermined value pressure-switch 334 opens circuit l310i When either of these pressure-switchesu334 or 337 open their respective circuits, alarms 335er 338 either light yup or` sound a bellto warn` the operator offthe break in electric power; Alarms 3354and 338 alsoioperatefif thesource .of power to circuits 310 or 311, respectively',is'interrupted,

When conversion'oil pressureincrease's to an abnormally `high pressure,.a` pressure indicatingcontroller 339 actuates ow control valve 281 ,to by-pass-a portion of the high pressure oilftherebyl Vregulating the conversion oil pressure to` the several reactors. f jAlso, valve 2,81 and rcontroller 339 operate to maintainv a predetermined pressure inoil conduit 201. y

' Likewise a pressure indicating lcontroller"336 .actuates -a flow control valve .275 in the tangentialnfuel 'conduit 214. to maintain the pressure at a predetermined value so as not toinadvertently increase thepressure in thevburners y.Circuits 310 and 311 connect with circuit 317 which connects with-the solenoid of a solenoid valve 27011 for closing oi or for admitting steam to boiler pumps through conduit 323 in case steam to these pumps is desired to be so controlled. l f

Circuit 311 communicates with circuit v314jby way of hand-switch 341`to the solenoid' valve 266. Hand-switch 341 is .providedI in casek it iseVer'deSired to -close down reactor 200 without closing down reactor 363. When it is`desired to close down reactor 200, upon actuating handswitch 341 the valve 266 closes ot instrument air pressure from conduit 233 and opens to bleed pressure from the diaphragms of valves 276 and 277 thereby closing valve 277 and opening 276' to conversion oil recycle. This circuit 311 also connects with circuit 315r which, when thejsolenoid of a three-way solenoid valve 264 is dce-energized, bleeds instrument air from the downstream side4 ofvalve 264 and thereby speeding actuation of the shutdown instruments downstream of this valve. Similarly, a solenoid valve 265 is actuated through circuit 318 or by opening hand-switch 340. Thus, by opening `hand-switch 340, the reactors `200 can be shut down without shutdowntof reactors 363. However, upon failure of electric power. in circuit 315, valve 264 will shut downthe reactors 363 without shutting down reactor 200. Pressure-switches 2911 and 292 are provided in circuit 315 and operate in response to pressure 4of the conversion Yoil in conduit 298 in such a manner that pressure-switch 29.2 actuates an alarm 294 when pressure of the conversion oil drops to a value below a `predetermined pressure, such as Y7,5 pounds per squarevinch gage, and pres- `Sure-switch 291actuates alarm 293 when pressure of the conversion oilin conduit 298 reaches a value greater than a prcdeterminedvalue such as pounds per square inch gage. Furthermore, a hand-switch 348 is provided for actuation of a solenoid valve 271 for venting air pressure from the diaphragrns of diaphragm valves 2,62 and 263. for control of valves `289 and 290. v

AISO, a branch circuit 316 connects with'l branch circuit- 315 `and leads by way of a hand-switch 349 to threeway solenoidvalve 268 -for closing valves 28,5 and; 286; talso,-.. another branch circuit leads, through a hand-switch 350for actuating Vthree-waysolenoid `v alve 269 for bleed- .ing air pressure from the diaphragms of valves 287 and 288 for closing valve 288 and opening valve 287.

Process air from conduitV 220, asmentioned before, .either passes on through this conduit and valve 279 or through by-pass conduit 221 and thence on to a 'conduit 222 for. passage-of at least a portion o f the air through `.preheater 211 and thence through a conduit 224 to the tangentialburners of reactor 200. A portion of the air .Y by-passes conduit 222 and flows through conduit 223. for

use as axialair in reactor 200.

3,24 to'. header 301:1.

A= ow recorder 3511 isl provided in conjunctionV with yconduit 29.6 for recording the ow n of tangential gas used m warming up reactors 363. A

'. Conduit 319. and conduit 321 conduct oit-gas from the respective bag. lter systems to Conduits 297 and 298 pass Vconversion oil to and from heat exchanger 301 for passageto conduit 299 into reactor 363 or forv recycle in conduit 300. j Thus, by the operationof the shutdown apparatus illustrated in :FIGURE 2 and described relative thereto by actuation. ofvthree-way vsolenoid valve 272, fthe entire sysblowers 360 and 361V blower.

tem is shut down; or, by actuation of solenoid valve 264, Y

the system of reactors 363 is shut down; or, by actuation of solenoid valve 265, the system of reactor Zilli is closed down. l

Thus, all reactors of bothV systems, as illustrated in power failure to the plant. Upon tangential gas or oil failure the HAF-ISAF reactors of both figures close down. Upon failure of conversion oil in theV system of FIGURE l both FEF-GFF and HAF-ISAF reactor operations shut down completely. Upon failure of conversion oil in the system of FIGURE 2, the feed oil to the FEF-GFF reactors goes on recycle and the line of reactors shuts down. The HAF-ISAF reactors go on feed oil recycle and continue running on inert gas operation, that is, anA excess air is used so as not to produce combustible constituents in the off gases.

Since the fur-V FIGURES 1 and 2, are entirely closed down upon electric nace efiiuent gases from the carbon black producing reactors contain hydrogen and carbon monoxide in appre- 'ciable proportions, any air drawn or injected into any of these gases from the reactors presents a particularly explosive hazard. Since the gases pass from the reactors through the headers to the bag-filter systems, the bag filter A Systems, the headers and conncctingconduits are particul' larly subject to possible explosions. v

That which is Vclaimed is: s l. In a system for production of carbon black by the incomplete combustion Vof a hydrocarbon charge stock including a reactor, an electric motor driven processeair j ond switches in said first and second circuits, respectively,

an electrical interlockv communicating said first circuit with said second switch, a fourth conduitleading from asource of instrument air, a 3-way electric motor operative valve 14 r Y third conduit,A a second valve inV said third conduit intermediate said vent conduit andA said blower, a third valve in said -second conduit, a fourth conduit. communicating said first conduit at a first point with said source` of charge stock, `a carbon black recovery system, a fifth conduit communicating said reactor with said'recovery system,

a lsixth conduit communicating said fifth conduit fork passage of-steam, a seventh conduit leading from a sourceV of noncombustion supporting gas to said recovery system, a second electric motor driven blower in said seventh conduit,.a `second vent conduit communicating with said seventh conduitintermediate said second yfblower and said recovery means, fourth, fifth, sixth, and seventh valves in,`

respectively, said sixth conduit, -second vent conduit, fourth conduit, and firstV conduit downstream of said first point, an emergency shutdown system operablein the event of an electric power'failure and in the event ofa process air supply failure, comprising firstand second electrical circuits communicating the motors of said rst and second blowerswith a source'of electrical power, a first switch in said second circuit, an electrical interlock operably connecting said'first circuit with said rst switch,

an eighth conduit leading from a source ofinstrument air, an electric motor operated 3-way valve in said eighth conduit, a third electrical lcircuit communicating Athe motor fof said motorV valve with a source of electrical power, a`

first pressure switch operably communicating said third conduit downstream'from said second valve with said third circuit, a` second pressure switch operatively communicating said eighth conduit downstream from lsaid motor valve, with said first circuit, first, second, third, fourth, fifth, sixth and4 seventh pressuresensing 'control means operatively communicating said eighth conduit, respectively, with said second, first, third, sixth, seventh, founth and fifthvalves whereby upon'relectric power fail-v ure, and` upon failure of rsaid processa'ir blower, the motor of said 3-wayvalve becomes de-energizedand the valve f closes'off said sourceof instrument air and opens a bleed from the downstream portion of said eighth conduit and -pressure therein decreases to Va value b'elowV 'a5 predeter- Y mined valuewhereby said rsecond pressure vswitch opens said first circuit thereby closing down said air blower'and via lsaid interlock closing down said second blower, and (said first pressure sensing Icontrol means closing 'said in saidfourth conduit, a third electrical circuit supply ,A ing electric vpowerto the motor of said valve, athird switch in said third circuit, a first pressure sensing means in communication with the rstvconduit passingrprocess air to said reactor and with said third switch, a second second valve, said first pressure switch opening said thirdV circuit whereby l,said SVV-way valve closes off said,

instrument air s upply'and vents pressure downstream of Vsaid 3-Way valve, and said second, fourth, fifth, third,

`sixth and seventh pressure sensing control means, re-

502 and closes said seventh valve, closing said third valve,

pressure sensing means communicating with saidrfourthl. conduit and withsaid first switch whereby upon sensing a pressure less than a predetermined pressure in said firstV conduit passing process air to said reactorV said, first pressure sensing means closes said third1 switch in said third circuit therebyv energizing the motor-of'said'motor valve therebyrclosing sameto said sourceof instrument air andreducing instrument air pressure insa1d fourth conduit on the side ofsaidvalve remote from said source of instrument air, said second pressure sensing means thereby sensing thedecreas'ed pressure in said fourthV conduit'y and opening said first switch thereby shutting down the electric motor driven process air blower and via said interlock opening said second. switch thereby shutting down the electric motor `driven repressuring 2. In a system for productioniof ct'irbon'blaclrV by incomplete combustion Yof a hydrocarbon charge' stock. including a reactor, a first conduit for supplying a hydrot carbon charge stock froml a source thereof to said reactor,

a secondV conduit supplying fuel VVunder pressure from a v source thereof to said reactor, a first electric rnotorv driven process air blower, a third lconduit'communicating said air blower with saidVV reactor, a first ventv conduitjpro-f vided with a -first vvalve and communicating with Ysaid spectively, opening said kfirst valve, opens said sixth valve opening said fourth valve and opening said fifth valve thereby.V closing down said `air and said noncombustion supporting (gas blowens; opening the valvesfin Saidvent conduits, closing olf air dov/,fuel flowfand hydrocarbon charge stock flow to said" reactor andtadmitting purgej e steam to said fifth conduit. l f

' 3 .V Ina system for production of carbon black bythe incomplete combustion Aof a hydrocarbonfcharge stock lincluding a reactona firstconduit for supplying a hydro' Y carbon charge stock fromV a source thereof to said reactor, a second conduit Vcornrrnmicating withsaid first conduit at "I a vfirst pointfor supplyingV atomizing air, a rstelectric Y motor -drivenprocessairblower, a third"co'nd uit cornmunicating said air `blower with said'reaotor, affirst vent conduit 'provided with a 1firstgvalveV communicating "with 'said third conduit, a second valve in said third conduit y n yintermediate said ventl conduit and V'said blower, a third `valve in said second conduit, a'fourth conduit communi' eating said Vfirstcor1,duit at a second point upstream' of,V J said rst'pointwithsaid source of charge stock, acarbon black recovery system, vajffth Vconduit, communicating .said reactorV with'fsaid recovery: system, a lsixth conduit f coimnunicating with said VfifthV conduit for passageV of steam,` a seventh` conduit leading from a Vsource of noncombustion supporting gase to said recoverysystem, a second electric motor driven blower in said seventh conduit, a second vent conduit communicating withv said seventh conduit intermediate said second blower and said recovery means, fourth, fifth, sixth and seventh valves in, respectively, said sixth conduit, second vent conduit, fourth conduit and first conduit downstream of said first point, an emergency shutdown system operable in the event of an electric power failure and in the event of a process air supply failure, comprising first and second electrical circuits communicating the motors of saidV first and second blowers with'a source of electrical power, a first switch in said second circuit, an yelectrical interlock operably connecting said first circuit with said first switch, an eighth conduit leading from a source of instrument air, an electric motor operated 3-way Vvalve in said eighth conduit, a third electrical circuit communicating the motor of said motor valve with la source of electrical power, a yrst pressure switch operably communicating said third conduit downstream from said second valve with said thirdvcircuit, a second pressure switch operably communicating said eighthrconduit downstream from said motor valve with said first circuit, rst, second, third, fourth, fifth, sixth and seventh vpressure sensing control meansoperatively communicating said eighth conduit, respectively, with said second, first, third, sixth, seventh, fourthand fifth valves, whereby upon electric power failure, and upon failure of said process air blower the motor of said 3-way valve becomes de-.energized and the valve closes ofi said source of instrument air and opens a bleed from the. downstream portion and pressure therein decreases to a value below a predetermined value whereby said second pressure switch opens said first circuit thereby closing down said air blower and Via said interlock closing down said second blower, and said first pressure sensing control means closes said second valve, said rst pressure switch opening said third circuit whereby said 3way valve closes ol said instrument air supply and vents pressure downstream of said 3-way valve and said second, fourth, fifth, third, sixth and seventh pressure sensing control means, respectively, opening said first valve, opening said sixth valve and closing said seventh valveclosing said third valve, Vopening said founth valve and opening said fifth valve thereby closing down said air and noncombustible supporting gas blowers; opening the valves in said vent conduits, closing off process air flow, atomizing air flow and hydrocarbon charge stock flow to said reactor and admitting purge ,steam to -said fifth conduit.

References Cited in the le of this patent UNITED STATES PATENTS 2,785,950 Ribble et al. Mar. 19, 1957 2,883,271 Pennington et al Apr. 21, 1959 2,886,567 Wood May'-12, -1959 3,038,788 l Y Pennington et al. June 12, 1962 

1. IN A SYSTEM FOR PRODUCTION OF CARBON BLACK BY THE INCOMPLETE COMBUSTION OF A HYDROCARBON CHARGE STOCK INCLUDING A REACTOR, AN ELECTRIC MOTOR DRIVEN PROCESS AIR BLOWER, FIRST CONDUITS SUPPLYING A HYDROCARBON CHARGE STOCK TO SAID REACTOR AND PASSING PROCESS AIR UNDER PRESSURE FROM SAID BLOWER TO SAID REACTOR, A SECOND CONDUIT FOR CONVEYING REACTION PRODUCTS FROM SAID REACTOR TO BAG FILTER CARBON BLACK RECOVERY EQUIPMENT, A THIRD CONDUIT COMMUNICATING SAID BAG FILTER RECOVERY EQUIPMENT WITH A SOURCE OF NONCOMBUSTION SUPPORTING GAS, AN ELECTRIC MOTOR DRIVEN BAG FILTER REPRESSURING BLOWER IN SAID THIRD CONDUIT, FIRST AND SECOND ELECTRICAL CIRCUITS SUPPLYING ELECTRICAL POWER TO THE MOTORS OF SAID PROCESS AIR BLOWER AND SAID REPRESSURING BLOWER, RESPECTIVELY, AN EMERGENCY SHUTDOWN SYSTEM COMPRISING, FIRST AND SECOND SWITHCHES IN SAID FIRST AND SECOND CIRCUITS, RESPECTIVELY, AN ELECTRICAL INTERLOCK COMMUNICATING SAID FIRST CIRCUIT WITH SAID SECOND SWITHC, A FOURTH CONDUIT LEADING FROM A SOURCE OF INSTRUMENT AIR, A 3-WAY ELECTRIC MOTOR OPERATIVE VALVE IN SAID FOURTH CONDUIT, A THIRD ELECTRICAL CIRCUIT SUPPLYING ELECTRIC POWER TO THE MOTOR OF SAID VALVE, A THIRD SWITCH IN SAID THIRD CIRCUIT, A FIRST PRESSURE SENSING MEANS IN COMMUNICATION WITH THE FIRST CONDUIT PASSING PROCESS AIR TO SAID REACTOR AND WITH SAID THIRD SWITCH, A SECOND PRESSURE SENSING MEANS COMMUNICATING WITH SAID FOURTH CONDUIT AND WITH SAID FIRST SWITHC WHEREBY UPON SENSING A PRESSURE LESS THAN A PREDETERMINED PRESSURE IN SAID FIRST CONDUIT PASSING PROCESS AIR TO SAID REACTOR SAID FIRST PRESSURE SENSING MEANS CLOSES SAID THIRD SWITCH IN SAID THIRD CIRCUIT THEREBY ENERGIZING THE MOTOR OF SAID MOTOR VALVE THEREBY CLOSING SAME TO SAID SOURCE OF INSTURMENT AIR AND REDUCING INSTRUMENT AIR PRESSURE IN SAID FOURTH CONDUIT ON THE SIDE OF SAID VALVE REMOTE FORM SAID SOURCE ON INSTRUMENT AIR, SAID SECOND PRESSURE SENSING MEANS THEREBY SENSING THE DECREASED PRESSURE IN SAID FOURTH CONDUIT AND OPENING SAID FIRST SWITCH THEREBY SHUTTING DOWN THE ELECTRIC MOTOR DRIVEN PROCESS AIR BLOWER AND VIA SAID INTERLOCK OPENING SAID SECOND SWITCH THEREBY SHUTTING DOWN THE ELECTRIC MOTOR DRIVEN REPRESSURING BLOWER. 